Getting Started with Codex
https://www.youtube.com/watch?v=px7XlbYgk7I
OpenAI released a detailed 53-minute workshop on how to start working with Codex, their code generation tool. The presentation covers all stages: from installation to advanced use cases.

Differences between Codex in the terminal (CLI), as a VS Code extension, and in the cloud. What the AGENTS.md file does. How to connect external services (e.g., Jira, Figma, documentation databases) via MCP servers.

https://www.youtube.com/watch?v=px7XlbYgk7I

Effective Prompting: Using @ to reference specific files. Ability to add screenshots (e.g., UI mockups) for code generation. Session restoration (codex resume) to continue working on complex tasks.

Advanced Scenarios: Code Review. Writing unit tests and documentation. Automated fixing of failed tests in CI/CD pipelines. Generating diagrams (Mermaid sequence diagrams) to explain code logic.

How Codex Works
https://openai.com/index/unrolling-the-codex-agent-loop/
Recently, distrust towards Anthropic has been growing, with many highlighting that Claude Code is not an open-source project. Against this backdrop, OpenAI has an opportunity to promote Codex. They released an article emphasizing that their project is open-source, allowing anyone to audit the code, and explained how it works.

At the core of Codex CLI is an "agent loop" that coordinates interaction between the user, the AI model, and tools. This loop repeats until the model provides a final text response. Constructing the initial prompt is a complex procedure: it consists of system instructions, a list of available tools (both built-in and external via MCP servers), and a description of the local environment.

Architecturally, Codex uses a stateless approach, moving away from the previous_response_id parameter. This means all necessary information is resent in every request, supporting a "Zero Data Retention" policy for enterprise clients. It is possible to use the gpt-oss model via Ollama 0.13.4+ or LM Studio 0.3.39+ entirely locally.

https://news.ycombinator.com/item?id=46737630
Many were pleasantly surprised by the transition to Rust (the codex-rs project), which has become the primary version, though some are confused by the npm installation method. The context compaction mechanism (/responses/compact) was highly praised as being superior to competitors.

#codex